Psychological stress and the risk of breast cancer: a case-control study

Objective: To determine whether psychological stress, in the form of past life events and stress at work, was associated with the development of breast cancer. Methods: The study was based on a case-control study of 257 women with breast cancer operated during 1993-1998 in Szczecin (Poland) hospitals and 565 controls, free of any cancer diagnosis. The subjects were sent a detailed questionnaire including questions on sociodemographic data; lifestyle (lifetime recreational and sport activities, occupational physical activity, diet); reproductive history; experience of psychological stress. The subjects reported major stressful life events, stress of daily activity and experience of stress at work. Logistic regression analyses were used to estimate the odds ratios (ORs) with 95% confidence intervals (CIs). Results: After adjustment for age and other potential confounders, we found that women with major life events, stress of daily activity, and depression had 3.7 times higher risk for breast cancer, compared to those which did not experience such stress (OR = 3.70; 95% CI, 2.61-5.26). Women who reported experience of stress at work had a nonsignificant 16% higher risk for breast cancer compared with those who reported no stress (OR = 1.16; 95% CI, 0.82-1.64). A higher proportion of cases (89.1%) than controls (71.1%) reported that their job was stressful, very fretful or very responsible or experienced a major life event (OR = 4.29; 95% CI. 2.66-6.92). Conclusion: These findings suggest an association between major life events and breast cancer. (C) 2004 International Society for Preventive Oncology. Published by Elsevier Ltd. All rights reserved.